Yeah, those are world files.
chunk_pc will be descriptors, anything starting with g_ is loaded directly onto the GPU by the game - so there's nothing in there but geometry or texture data - not even the dimensions are in those files.
Source code is here, knock yourself out
PegTool's code is fairly dodgy - it was originally what I was using for my experiments and I never got around to cleaning it up
Awesome, thanks. This is a good excuse for me to brush up on C#.
So the chunk_pc files contain information about the textures in the g_ files that is needed to extract them, it's just a matter of figuring out the chunk_pc format (similar to peg_pc, probably?). Otherwise, getting the textures out is...more difficult.